Methods are described for reducing shot noise in magnetic-film memories which are to be read magnetooptically with the auxiliary aid of an electron beam. In such memories the principal source of shot noise is from the light which is used to illuminate the memory array. The following methods of reducing array shot noise are considered: 1) selective background, 2) magnetooptical balance, 3) temperat...
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A random-access magnetic-film memory with a desired bit density ρLof 108/cm2is postulated with writing and reading each to be performed with a deflectable electron beam within 1 μs. Curie point writing is suggested, while detection of the deflection of electrons due to the Lorentz force is proposed for readout. The transmission, reflection, mirror, and im...
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This simulation is intended for use at low, intermediate, and high bit densities. While simpler algorithms can be found for use with either very low bit densities only, or with very high bit densities only, they lack the generality needed for this purpose. The simulation is composed of three distinct sequential computations. First, using a noninteracting particle idealizedM_{r}-Hmodel a...
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The experimental results are reported for a series of measurements made on a single-crystal gadolinium garnet, with a view to obtaining the characteristics which appeared necessary for the use of garnets as memory elements. In particular, variations in the hysteresis loop as a function of the temperature are discussed in order to obtain the dependence of the rectangularity on the temperature. The ...
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Attempts have been made to interpret magnetic annealing effects by assuming that the uniaxial anisotropy is caused by a directional order of local atomic configurations. By studying both evaporated and electroplated films, it is found that during an anneal the number of such elementary anisotropy sources is conserved. The angular dependence of magnetic annealing effects can be described by assumin...
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A new type of wall coupling previously considered implausible has been observed in coupled Permalloy films 2000 Å thick and 2 microns apart. The walls separate antiparallel domains oriented along the easy axis and zigzagging perpendicularly to it. A model for the magnetization distribution in the transition region between oppositely magnetized domains has been proposed for the evaluation of t...
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Creep measurements were made on single domain walls in thin magnetic films using high-speed pulses with variable rise and fall times (0.4 ns to>1 mus) and durations (<1 ns to 3 μs). Combinations of these pulses and dc fields were applied along the hard axis while simultaneously easy-axis dc fields were applied. The two basic measurements that were made were onset of creep and...
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A 4-K-word 50-bit-per-word plated wire main memory was constructed and tested at a 200-ns cycle time. 32 matrix planes were constructed of the woven wire type (each plane contained 128 words and was stacked into 2 blocks for a total capacity of 4 K words). Special design features for high-speed operations are 1) memory stack construction with memory planes which are serially connected with grounde...
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The rotational astroid of uniaxial thin films may be obtained from the cross-field loopm_{x} , h_{y}graphically or electronically by assuming Slenczewski's tangent rule. The graphical construction by means of the tangent rule is demonstrated. The derivation of the transformation to obtain the astroid electronically is given, and a comparison is made with astroids obtained graphically as...
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Investigations of square-loop ferrite toroids have established that disturbed 1 and 0 signals, as well as delta noise, are a function of the location of the drive wire within the aperture of the core. Experimental results indicate that the disturbed 0 as well as the delta noise increases as the relative displacement of the drive wire from the center of the core is increased. The disturbed 1 decrea...
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The guided-flux technique as described for the first time in 1963 [1] is generally considered as one of the most interesting all-magnetic techniques, mainly because it has no theoretical speed limitation. At the present time, no theoretical analysis of systems using this technique is available. The design of a shift register is discussed, and the way the shape of the element may be changed in orde...
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Residue arithmetic and digital balanced magnetic circuits have been separate objects of research in the last ten years. This paper points out certain potentially interesting areas for them to be considered together. Following a review, the concept for a residue arithmetic unit capable of forming sums and products at the same time is described. A small balanced magnetic residue arithmetic unit was ...
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Active device application feasibility of single-crystal CdCr2Se4, a ferromagnetic semiconducting spinel, has been demonstrated by the successful fabrication of p-n junctions which operate below the Curie temperature. The junction construction techniques and some of the characteristics of the junctions are discussed.
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The recently developed "current stretch" technique, a low temperature integration and amplification of sense signals, offers new freedom in the design of cryogenic memory cells. This scheme makes the sense voltage independent of cell switching speed and gives a good signal-to-noise ratio. A memory system using a double hole tin film storage cell driven by cryotron trees is described. Current stret...
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The chopper voltage regulators using a diode and an LC filter for output rectification and filtering are widely used in dc-to-dc conversion. Three possible configurations are 1) a series connection of the filter choke and switch with the load, 2) a series connection of the choke and the parallel connection of the switch with the load, and 3) a series connection of a chopper and the parallel connec...
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A brief description is given of a recently published method for measuring the linewidth of single-crystal ferrites. A theoretical analysis is made of the errors caused by the deviation from the ideal of two of the components in the test apparatus. These deviations include a VSWR greater than unity due to the input isolator and the finite directivity of the directional coupler. The range of possibl...
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A study was made of the change in anisotropy field, coercivity, angular dispersion, and creep threshold of an ordinary Ni-Fe film when coupled with a stripe-domain film. It was found that the values of these properties all increased as a result of the coupling.
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Relationships among dispersion, switching thresholds, ripple theory, the switching astroid, and the Landau-Lifshitz equation are indicated. It is conjectured that film dispersion should be less than a critical value of about 2 degrees if the influence of the switching astroid is to be prominent.
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